Why outbound from a practice usually reads badly
The instinct is to describe the services: bookkeeping, payroll, VAT, year-end. The recipient already has all of that from somebody, so a service list is an invitation to delete. What earns a reply is a sentence that shows you looked at the company — its size, its growth, the fact that it just opened a second entity — followed by one plain reason that might matter to them.
That is a research problem before it is a writing problem, and research is the part a firm never has capacity for. The agent reads the company before it writes, and the draft you review either contains a real observation or it does not — which makes it easy to judge.